Removed unused imports, resources, and any un-used code that caused Lint errors/warnings

There was an enormous amount of Lint errors and warnings caused by unused imports, unused resources (layouts, drawables, etc.), and even completely unused private methods. Removed everything that was unused and no errors were caused by doing so.

It is now highly optimized and will most likely run faster when implemented in apps (I'm actually using it in one of my own apps that are currently under development). Also, I changed the target API level to 17 (4.2 Jellybean), the minimum is still the same so that won't really affect anything.